1. Field of the Invention
The present invention relates to a battery pack and more particularly to a battery pack having an improved short circuit prevention mechanism.
2. Description of the Related Art
In general, a single battery cell may be insufficient as a power source for a notebook PC, etc. Therefore, a battery pack is provided as a power source, the battery pack including a plurality of battery cells connected in a row and/or in series, the battery pack providing a desired voltage and capacity. A conductive plate is generally used for connecting a plurality of battery cells in a row and/or in series. A charge/discharge control circuit and/or a protective circuit may be installed in the battery cells, such battery cells being accommodated in a case with various circuits.
Referring to FIG. 1a, a first conductive plate 21 is fixed to battery cells 1, 2, a second conductive plate 22 is fixed to battery cells 1, 2, 3, 4, a third conductive plate 23 is fixed to battery cells 3, 4, 5, 6 a fourth conductive plate 24 is fixed to battery cells 5, 6, 7, 8, and a fifth conductive plate 25 is fixed to battery cells 7, 8 by welding, the sides of individual battery cells having different polarities. A protruding terminal of each battery cell represents a positive electrode and a flat terminal of each battery cell represents a negative electrode.
Conductive plates 22, 23, 24 have generally centrally located bendable portions. A first portion of the conductive plates 22, 23, 24 located on a first side of the bendable portion is fixedly connected to a positive electrode and a second portion of the conductive plates 22, 23, 24 located on a second side of the bendable portion is fixedly connected to the negative electrode such that the battery cells can be connected with each other in series or in a row. The conductive plates 21 and 25 electrically connect battery cells having the same polarities in a row.
FIG. 1b shows the battery cells when the conductive plates 22, 23, 24 have been bent about the bendable portions thereof. In FIG. 1b, B+ and B− represent current terminals, i.e., power source sections provided at either side end of the battery cells connected in series or in a row. Here, B+ is a positive electrode power source section serving as the highest potential terminal, and B− is a negative electrode power source section serving as the lowest potential terminal. A power source terminal tap may be connected to the current terminals to supply power. The conductive plate may be fabricated with a shape of a “T” or “⊥”, wherein a horizontal part “—” is fixed to the positive electrode or the negative electrode by welding, and a vertical part “I” is fixed to the power source terminal tap by soldering. The conductive plate may be integrally formed with the power source terminal tap.
In addition, B1, B2 and B3 represent sensing terminals, where electrodes of battery cells having different polarities are connected in series. The sensing terminals B1, B2, B3 refer to intermediate potential terminals aligned between the highest potential terminal B+ and the lowest potential terminal B−. A sensing terminal tap may be connected to the sensing terminals B1, B2, B3 to detect voltage. The conductive plate may be fabricated with a shape of a “T” or “⊥”, wherein a horizontal part “—” is fixed to the positive electrode or the negative electrode by welding, and a vertical part “I” is fixed to the sensing terminal tap by soldering. The conductive plate may be integrally formed with the sensing terminal tap.
The power source terminal tap and the sensing terminal tap may both be described as “terminal taps.” The terminal taps may be fabricated in the form of a wire or an elongated plate and may be made from nickel-containing metal.
The sensing terminal tap is not shown in FIG. 1b. A power terminal tap 31 extending from the conductive plate 21 provided at the B− terminal is connected to a circuit section of a printed circuit board (PCB) along surfaces of battery cells 1, 2 connected in series. In addition, a power terminal tap 32 extending from the conductive plate 25 provided at the B+ terminal is connected to the circuit section of the PCB.
Referring to FIG. 1c, the conductive plate 23 has a generally rectangular shape and has a generally centrally-located bendable portion 23d. A first-half part 23b of the conductive plate 23 may be welded to a top surface of the battery cell having positive polarity and a second-half part 23a of the conductive plate 23 may be welded to a bottom surface of the battery cell having negative polarity. In addition, the conductive plate 23 may include a terminal tap connection part 23c to which the terminal tap is connected. The terminal tap connection part 23c may be integrally formed with the first-half part 23b or the second-half part 23a of the conductive plate 23.
Referring to FIGS. 1b to 1d, the bendable portion 23d of the conductive plate 23 protrudes between battery cells 4, 6 at the sensing terminal B2. In addition, the power source terminal tap 31 extends in the vicinity of the bendable portion 23d. Accordingly, it is desirable to provide a device for preventing a short circuit from occurring between the bendable portion 23d and the power source terminal tap 31. Insulating tape 42 (FIG. 1b) may be attached onto transparent tape 43 used for fixing the battery cells 4, 6, and the power source terminal tap 31 may be surrounded by an insulating cover 41.
Although this structure can insulate between the bending portion 23d and the terminal tap (power source terminal tap 31) extending adjacent to the bending portion, a space formed between a case 70 (FIG. 1d) of the battery pack and the battery cell 6 is reduced as the size of the battery pack is minimized. In addition, since ends of the bending portion 23d may have sharp edges, various insulating members 41, 42 may be damaged by the side ends of the bending portion 23d when a device equipped with the battery pack vibrates. In this case, a short circuit may occur between the bending portion 23d of the conductive plate and the terminal tap 31, degrading the function of the battery pack.
Although bendable portions of the conductive plates 22, 24 also protrude between battery cells at the sensing terminals B1 and B3, since the terminal tap does not extend adjacent to the bending portions of the conductive plates 22, 24, a short circuit is less likely to occur between the bendable portions and the terminal tap.